The aperture is an expandable ring inside the body of the camera which is measured in f stop (see diagram). Aperture can also control depth of field, a small f stop can offer a shallow depth of field whereas a larger f stop can offer a wider depth of field for example taking a school photograph, whereas you may want a shallower depth of field on a macro wildlife photography or portraiture.
1) How will the size of aperture affect exposure?
A larger aperture hole (smaller f-stop) will let in more light meaning the image will be brighter whereas a smaller aperture hole (larger f-stop) will let in less light.
2) What potential problems could this create?
By having the aperture hole too larger you could over exposure your image on a bright day and if the hole is too small on a darker day the shutter speed will be slower so you may experience camera shake and blurring of the image.
3) How could you compensate these problems?
The ISO is probably the easiest option to compensate these problems, on a brighter day use a lower ISO (about 100) which makes the camera filter less light sensitive and on a darker day or inside use a higher ISO (can range from 800 -3200) to make the filter more light sensitive.